1. Field of the Invention
The present invention relates to a fuel injection apparatus for an internal combustion engine, the apparatus comprising a fuel injector equipped with an air-assist unit for atomizing fuel ejected from the fuel injector by blowing air, to thereby improve the combustion and fuel consumption of the internal combustion engine.
2. Description of the Related Art
In general, to ensure that an internal combustion engine attains an effective combustion with a small amount of fuel, it is necessary to supply the fuel into a combustion chamber in an optimum burnable condition.
Accordingly, internal combustion engines equipped with current fuel injectors are provided with fuel injection apparatuses each including an air-assist unit for improving the atomization of the ejected fuel; this unit blowing air from the outside in the vicinity of a fuel injection nozzle opening of the fuel injector (ex. Japanese Unexamined Patent Publication No. 1-271634, Japanese Unexamined Utility Model Publication No. 1-61461 etc.,).
In the above-mentioned conventional apparatus, an adaptor having air-assist holes through which air from the air-assist unit is blown out is attached to a fuel-injection end of the fuel injector. Further, close to the air-assist holes, the adaptor is provided with mixture injection ports for diverging and ejecting a mixture of the fuel and assist air in the desired directions.
In the conventional adaptor, however, since the air-assist holes are arranged close to the mixture injection ports, as soon as the fuel is mixed with the assist air, the mixture is immediately ejected through the adaptor. Consequently, the mixture is diverged into some of the mixture injection ports in an unstable flow condition, and therefore, the fuel cannot be always evenly divided among the mixture injection ports and thus the amount of fuel supplied to an intake port will vary and the combustion of the engine will be unstable.
In addition, due to instability of the flow of the mixture, the directions of movement of the fuel particles are complicated, and thus the mixture ejected from the mixture injection ports is immediately diffused, and accordingly, it is impossible to eject the fuel mixture in the desired direction.